The invention relates to a universal joint and particularly to a Cardan type cross coupling comprising two coupling halves or forks and a stop which can be smoothly adjusted axially to restrict the bend angle between the coupling halves. The stop may be located radially outside the cross coupling.
The foregoing device is found especially in cross couplings used in heavy machinery, e.g. in the drives of rolling mills, i.e. where the shafts have large dimensions. Such shafts cannot be brought manually into the necessary assembly position and be pushed into the centering arrangement, due to the weight and the friction in the couplings. For example, when the rollers are being changed, the shafts have to be supported by lifting tools and the freely movable coupling halves must be lined up in the assembly position.
An assembly aid already exists in the form of the pivot-angle restriction known from German Petty Patent DE-GM 77 16089. In this case, fixed stops on the coupling halves ensure that a coupling half bends only up to a maximum pivot-angle, which lies just above the bend angle which occurs during operation. Another bend angle restriction is known from German Patent De-PS 2,711,177. In this case, two bolts, which are attached one to each coupling half and which penetrate into a central bore in the journal cross, restrict the angular movement of the coupling by resting on each other. Another bend angle restriction is disclosed in U.S. Pat. No. 4,195,495, which consists of two tubular sleeves, one attached to each of the coupling halves. These sleeves surround the coupling and come into contact with each other when the maximum bend angle is reached. The maximum bend angle can be adjusted by rotating the tubular sleeves. SE-AS 420,640 disclosed the maximum bend angle being restricted by a stop on two hemispherical parts which slide into each other and which enclose the coupling. A further bend angle restriction is known from U.S. Pat. No. 3,339,379 in which hook-shaped restricting members prevent the coupling from bending too much.
A disadvantage with the known devices is that after the adjoining machine part, e.g. a roller, has been removed, the coupling can move freely and drops downward under its weight until it reaches its stop. This makes subsequent re-assembly considerably more difficult. In addition, the permissible bending of the coupling during operation is considerably restricted.